Accurate peak fitting and subsequent quantitative composition analysis of the spectrum of Co 2<i>p</i> obtained with Al Kα radiation: I: cobalt spinel

Cabrera-Germán, D.; Gómez‐Sosa, Gustavo; Herrera-Gómez, Alberto

doi:10.1002/sia.5933

Cited by 122 publications

(79 citation statements)

References 24 publications

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“…The intensity of the satellite features appears to be enhanced indicating a contribution from the presence of Co(OH) 2 and phosphate species on the surface. 52 As shown in Figure 1h, two peaks, P 2p 3/2 and P 2p 1/2 , were also present in the P 2p region at 132.3 and 133.2 eV, respectively. These peaks are consistent with the characteristic binding energies of tetrahedral (PO 4 ) groups.…”

Section: Preparation and Characterization Ofmentioning

confidence: 78%

Cobalt Phosphate Nanostructures for Non-Enzymatic Glucose Sensing at Physiological pH

Tomanin

Cherepanov

Besford

et al. 2018

ACS Appl. Mater. Interfaces

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Nanostructured materials have great potential as platforms for analytical assays and catalytic reactions. Herein, we report the synthesis of electrocatalytically active cobalt phosphate nanostructures (CPNs) using a simple, low-cost, and scalable preparation method. The electrocatalytic properties of the CPNs toward the electrooxidation of glucose (Glu) were studied by cyclic voltammetry and chronoamperometry in relevant biological electrolytes, such as phosphate-buffered saline (PBS), at physiological pH (7.4). Using the CPNs, Glu detection could be achieved over a wide range of biologically relevant concentrations, from 1 to 30 mM Glu in PBS, with a sensitivity of 7.90 nA/mM cm 2 and a limit of detection of 0.3 mM, thus fulfilling the necessary requirements for human blood Glu detection. In addition, the CPNs showed a high structural and functional stability over time at physiological pH. The CPN-coated electrodes could also be used for Glu detection in the presence of interfering agents (e.g., ascorbic acid and dopamine) and in human serum. Density functional theory calculations were performed to evaluate the interaction of Glu with different faceted cobalt phosphate surfaces; the results revealed that specific surface presentations of undercoordinated cobalt led to the strongest interaction with Glu, suggesting that enhanced detection of Glu by the CPNs can be achieved by lowering the surface coordination of cobalt.Our results highlight the potential use of phosphate-based nanostructures as catalysts for electrochemical sensing of biochemical analytes.Potassium chloride (KCl, CAS no. 7440-09-7) was purchased from Chem-Supply. All the chemicals were used as received. High purity (Milli-Q) water with a resistivity of 18.2 MΩ cm was obtained from an inline Millipore RiOs/Origin water purification system.Instrumentation. X-ray photoelectron spectroscopy (XPS) spectra were acquired using an Axis Ultra X-ray photoelectron spectrometer (Kratos Analytical, UK), equipped with a 165 mm concentric hemispherical electron energy analyzer and a monochromated Al Kα incident Xray source (1486.6 eV). Survey (wide) scans were recorded in the binding energy range of 0-1200 eV, with 1.0 eV steps, a dwell time of 100 ms, and an analyzer pass energy of 160 eV.Multiplex (narrow) high-resolution spectra were recorded with a pass energy of 20 eV, with 0.05 eV steps, and a dwell time of 250 ms, resulting in an energy resolution (ΔE/E) of ~300 meV. The base pressure in the analysis chamber during data collection was 1-2 × 10 −9 mbar, and these data were processed using the software CasaXPS. All binding energies were calibrated using the C 1s level of adventitious carbon at 285.0 eV. Fourier transform infrared (FTIR) spectra were obtained on a Tensor II (Bruker) attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrometer and analyzed using the software OPUS 7.8. The number of scans was 64. A minimum resolution of 4 cm −1 and the absorbance/transmittance mode were used. Scanning electron microscopy (SEM) images were o...

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Section: Preparation and Characterization Ofmentioning

confidence: 78%

Cobalt Phosphate Nanostructures for Non-Enzymatic Glucose Sensing at Physiological pH

Tomanin

Cherepanov

Besford

et al. 2018

ACS Appl. Mater. Interfaces

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“…The spectra quantification was done employing an approach that evaluates the signal attenuation due to inelastic and elastic scattering . The method has been proven successful in the chemical assessment of other first‐row transition metal oxides (Co 3 O 4 and Fe 2 O 3 ) and in many other materials reported by this group and others. The composition of a zinc oxide overlayer was evaluated considering that the atomic density ( ρ S ) of each element ( S = Zn 2 p [metal], Zn 2 p [oxide], O 1 s , C 1 s ) is related to the corresponding peak intensity ( I S ) through the following set of equations:

I_{S} ((), α) = C ρ_{S} \frac{normald σ_{S}}{normald Ω} A_{S} λ_{S} sin α ([], 1 - exp ((), - \frac{d_{S}}{λ_{S} sin α})) \prod_{i}^{\begin{matrix} center \\ center layers \\ center above S \end{matrix}} exp ((), - \frac{d_{i}}{λ_{S, normali} sin α}),

where d σ S /d Ω is the differential photoelectron cross section of core level S , A S is the efficiency of the spectrometer at the associated electron kinetic energy, λ S is the effective attenuation length as the photoelectron travels through the layer containing species S , d S is the thickness of such layer, α is the take‐off angle, λ S , i is the effective attenuation length of the photoelectrons from species S as they travel through layer i in the way out to the surface (so the last factor is the attenuation caused by the material above layer S ), d i is the thickness of layer i , and C is an overall constant (the same for every species) that depends on the X‐ray flux and other geometrical parameters .…”

Section: Resultsmentioning

confidence: 99%

Detailed peak fitting analysis of the Zn 2p photoemission spectrum for metallic films and its initial oxidation stages

Cabrera-Germán

Molar-Velázquez

Gómez‐Sosa

et al. 2017

Surface & Interface Analysis

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The metallic Zn 2p photoemission spectra hold a complex background that requires individual assignment of Shirley background for each peak comprising the spectra. For this reason, a close fit requires the use of the Shirley‐Vegh‐Salvi‐Castle background‐type under the active background approach. We found that the intensity of the plasmon peaks and their associated background cannot be described through existing energy loss (intrinsic and extrinsic) formalisms. We also analyzed the Zn 2p and O 1s spectra for the initial stages of oxide formation at various oxygen exposures. We found that the composition of the oxide layer is ZnO1.00±0.10 for all exposures, suggesting that our assessment of the primary function of metallic Zn is accurate and can be employed for quantitative studies. We also present a set of parameters to accurately fit and resolve the metallic and oxide Zn 2p peaks.

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“…As can be seen in Fig. 3(a), the Ni 2p spectra for NiMoSAC was Meanwhile, the Co 2p spectrum was fitted considering a LMM Auger peak at 774.6 eV, 43 cobalt sulfide phases Co x S y like Co 2 S 3 , Co 9 S 8 , or CoS (BE at 778.4 eV), 37,44 a peak at 779.4 eV arising from the CoMoS phase, cobalt oxide (Co OX ) with BE at 782.5 eV, which is close to that of Co in Co 2 O 3 (781.4 eV) or Co(OH) 2 (782 eV) but not with the BE of Co in CoO (780 eV), 12 as shown in Fig. 3(c).…”

Section: B Mo-speciesmentioning

confidence: 99%

Relevant changes in the properties of Co(Ni)Mo/Al₂O₃HDS catalysts modified by small amounts of SiO₂

et al. 2018

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The changes in hydrodesulfurization activity, selectivity, dispersion, sulfidation, and extent of promotion of Co(Ni)Mo catalysts were investigated when the alumina support surface is modified by grafting 4 wt% silica. Adding SiO 2 eliminates the most reactive hydroxyl groups on the alumina surface (IR band at 3775 cm À1 ) decreasing the possibility of generating tetrahedral Mo species difficult to sulfide in favor of octahedral ones capable of contributing to the sulfided active phase. The catalysts were evaluated in the hydrodesulfurization of 4,6-dimethyldibenzothiophene. Incorporating SiO 2 to alumina increases the hydrogenation rate constant and therefore the global hydrodesulfurization rate of 4,6-dimethyldibenzothiophene and enhances the promotion of Mo by Co (or Ni). The global sulfidation of Ni is not affected by the addition of silica but the sulfidation of cobalt is significantly improved. The extent of promotion of the NiMo/Al 2 O 3 and NiMo/SiO 2 / Al 2 O 3 catalysts was greater than the one achieved in their Co-promoted counterparts.

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Accurate peak fitting and subsequent quantitative composition analysis of the spectrum of Co 2p obtained with Al Kα radiation: I: cobalt spinel

Cited by 122 publications

References 24 publications

Cobalt Phosphate Nanostructures for Non-Enzymatic Glucose Sensing at Physiological pH

Cobalt Phosphate Nanostructures for Non-Enzymatic Glucose Sensing at Physiological pH

Detailed peak fitting analysis of the Zn 2p photoemission spectrum for metallic films and its initial oxidation stages

Relevant changes in the properties of Co(Ni)Mo/Al₂O₃HDS catalysts modified by small amounts of SiO₂

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Accurate peak fitting and subsequent quantitative composition analysis of the spectrum of Co 2p obtained with Al Kα radiation: I: cobalt spinel

Cited by 122 publications

References 24 publications

Cobalt Phosphate Nanostructures for Non-Enzymatic Glucose Sensing at Physiological pH

Cobalt Phosphate Nanostructures for Non-Enzymatic Glucose Sensing at Physiological pH

Detailed peak fitting analysis of the Zn 2p photoemission spectrum for metallic films and its initial oxidation stages

Relevant changes in the properties of Co(Ni)Mo/Al2O3HDS catalysts modified by small amounts of SiO2

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Relevant changes in the properties of Co(Ni)Mo/Al₂O₃HDS catalysts modified by small amounts of SiO₂